Adding gypsum after fermentation

Question

I have found resources that both advocate and highly advise against this practice. We recently brewed a IIPA (Bear Flavored's Heady Topper clone) that has 3lbs of hops, plus hop extract in 14 gallons. We didn't add any gypsum to our 4ppm sulfate water. I want to make this the best beer possible. I tried adding untreated gypsum to a prior IIPA (in the glass) and wasn't thrilled with the results.

Questions:

-Why does adding gypsum to the strike water/mash differ from adding it to the glass, or to the beer post fermentation? -Would there be any way to mimic adding it to the mash after fermentation? Maybe making a heavily gypsum-ized starter beer, fermenting it, and blending? -What about adding gypsum to boiling water, chilling and adding that to the beer? Does boiling salts change the way they behave on the palette or diffuse into the beer?

Answer 1

Gypsum does two things:

1. It releases calcium ions into the mash, which combine with phosphates from the grain to create an acid, thus acidifying the mash.

2. It provides sulphate ions which contribute a flavour. It's widely reported that sulphates accentuate hop bitterness and give a slight saltiness to the beer.

If you took all your gypsum and added it only to the glass, then you'd miss out on the first point. However, if you can get the mash pH in line using other means (e.g. acidulated malt), then it's quite reasonable to add salts to the glass or during packaging.

John Palmer advocates this in his book Water. I have tried it - preparing known quantities of various salts and adding them to different beers to observe the effect. It does produce a taste difference, although it takes some finesse to improve the beer this way.